Unravelling the phylogeny and bioactivity of endophytic Colletotrichum aeschynomenes isolated from Thottea siliquosa

Endophytes inhabit the internal tissues of living organisms without causing any symptoms in their hosts. These endophytes often produce metabolites responsible for bioactivities, such as antimicrobial and antioxidant activities. In the present work, we isolated the fungus Colletotrichum aeschynomenes as an endophyte from the leaf of Thottea siliquosa (Lam.) Ding Hou. The identity of the fungus was confirmed by sequencing the ITS gene, followed by phylogenetic analysis with 10 closely related species. Phylogenetic analysis confirmed the fungus as C. aeschynomenes, with our query sequence forming a sister clade to the GenBank sequence (ICMP 17673). The ethyl acetate extract of the fungus contained proteins, flavonoids and steroids. The concentrations of proteins, phenolics, and flavonoids in the dried extract were 0.388-0.02 mg/mg, 0.306-0.09 mg mg , and 0.638-0.038 mg/mg, respectively. With the assumption that -1 the high concentration of secondary metabolites could lead to significant bioactivity, the extract was tested for antibacterial and antioxidant activities. The fungal extract showed relative inhibition against S. aureus (85.43%), B. cereus (80.81%), E. coli (73.33%), and P. aeruginosa (68.66%). The IC value for DPPH 50 radical scavenging was 1 mg ml , while for ABTS, it was 0.2 mg/ml. GC-MS analysis of the extract -1 revealed the presence of several bioactive metabolites, which may serve as potential drugs to treat many pathogens.. KEYWORDS :Antibacterial activity, antioxidant activity, Colletotrichum aeschynomenes, endophyte, Thottea Siliquosa